Neighbor class and disconnected polygons

Helper

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On 06/07/2012 at 09:58, xxxxxxxx wrote:

Thanks.
I'm new to this whole ASCII, Unicode, etc.. stuff. And I'm trying to figure it all out.

-I still don't see how you're getting a BOOL value from a UCHAR array.
-I would also like to know how to convert a UCHAR value to a String value. If that's possible.

-ScottA

Helper

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On 06/07/2012 at 10:25, xxxxxxxx wrote:

Well... a Cinema 4D SDK "Bool" is actually typdef'd as an 'int', which would be a 32bit or 64bit value, but the typical use of such a variable is just to store true or false, 1 or 0... which only needs a single bit to represent, but the compiler/cpu can access a 32bit/64bit value just as fast.

Since a Bool is either 32bits or 64bits (depending on the OS and Compiler options), I am using an 8bit 'unsigned character' (a UCHAR) instead, to save some memory. I am just using it to store 1 or 0 - true or false.

So, because of the way C/C++ works, I can test the byte for being 'non-zero'...

  
UCHAR b = 0;  
  
if( b ) ...  // would evaluate to false.  
  
b = 1;  
  
if( b ) ... // b is now 'non-zero', so it evaluates to true.  
  
b = 255;  
  
if( b ) ... // b is still non-zero, so it evaluates to true.  
  
char *ptr = NULL;  
  
if( ptr ) ... // since ptr is NULL ( zero ), it evaluates to false.  
  
char mystring[] = "hello world";  
ptr = mystring; // or ptr = &mystring[0];  
  
if( ptr ) ... // since ptr now points to something, it has a non-zero/non-NULL value, so it evaluates to true.  
  
String c4dStr = String(mystring);        // convert char C string to Cinema 4D String  
String c4dStr = String("hello world"); // that also works  
String c4dStr = "hello world";             // so does that  
  
String c4dStr = "hello";  
c4dStr += " world";                           // you can also concatenate...  
  
String c4dStr = String("hello")+String(" world");  // but you might have to use the String() form to add/concatenate on the same statement.

...basically any value except 0 (or NULL, for pointers) evaluates to true.

For ASCII values, do a google search to find a chart like this one... where you can see (for example) the ASCII value for the character '0' is the value 48 decimal, so...

  
char mystring[12];  
mystring[0] =   72;  // H  
mystring[1] =  101;  // e  
mystring[2] =  108;  // l  
mystring[3] =  108;  // l  
mystring[4] =  111;  // o  
mystring[5] =   32;  // <space>  
mystring[6] =   87;  // W  
mystring[7] =  111;  // o  
mystring[8] =  114;  // r  
mystring[9] =  108;  // l  
mystring[10] =  100; // d  
mystring[11] =    0; // null termination.  
  
String c4dStr = String(mystring);  
GePrint(c4dStr);   // prints...    "Hello World" (without the quotes)

Helper

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On 06/07/2012 at 11:10, xxxxxxxx wrote:

Thanks for the explanation.
I understand how you're getting the BOOL now.

I think I was misunderstanding what a UCHAR is. Please check my thinking on this.
UCHAR is used to store values. Specifically positive values. Not characters as the name seems to imply.
The same way a DWORD stores unsigned long values. Not strings as the name seems to imply.
So there is no such thing as converting a UCHAR to a string.

Is that correct?

-ScottA

Helper

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On 06/07/2012 at 11:13, xxxxxxxx wrote:

...Just for completeness (I'm still not clear exactly what you're asking/trying to accomplish)...

If you literally want to print the values of a UCHAR array, you can still do that fairly easily...

  
    GePrint(String("PolyProcessed[0] = ")+LongToString((LONG)PolyProcessed[0]));

...you could even leave out the (LONG) cast (it would get cast anyway - I just added it for clarity).

Helper

THE POST BELOW IS MORE THAN 5 YEARS OLD. RELATED SUPPORT INFORMATION MIGHT BE OUTDATED OR DEPRECATED

On 06/07/2012 at 11:15, xxxxxxxx wrote:

Originally posted by xxxxxxxx

Thanks for the explanation.
I understand how you're getting the BOOL now.

I think I was misunderstanding what a UCHAR is. Please check my thinking on this.
UCHAR is used to store values. Specifically positive values. Not characters as the name seems to imply.
The same way a DWORD stores unsigned long values. Not strings as the name seems to imply.
So there is no such thing as converting a UCHAR to a string.

Is that correct?

-ScottA

Yes - you are correct - I'm using it to just store some value between 0 - 255 (and in this case, just either 1 or 0).

An array of UCHARs is actually a C string, by definition and can be used as such as long as it's null-terminated (erm... and as long as it contains printable characters - but not how I'm using it).

Again, just for completeness/correctness... you can in fact store characters in a UCHAR array...

  
mystring[0] =  'H';  // H  
mystring[1] =  'e';  // e  
mystring[2] =  'l';  // l  
mystring[3] =  'l';  // l  
mystring[4] =  'o';  // o  
mystring[5] =  ' ';  // <space>  
mystring[6] =  'W';  // W  
mystring[7] =  'o';  // o  
mystring[8] =  'r';  // r  
mystring[9] =  'l';  // l  
mystring[10] =  'd'; // d  
mystring[11] = '\0'; // null termination.

...the above is equivalent to my previous post, just using characters instead of the equivalent ASCII values that represent those same characters.

Helper

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On 06/07/2012 at 12:05, xxxxxxxx wrote:

Thanks a lot for explaining this stuff.
I did some searching on WCHAR to see If it could help me learn more about UCHAR. But you've eplained it quite well.

Thank you.
-ScottA

Helper

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On 03/08/2012 at 04:43, xxxxxxxx wrote:

Just a heads up: there is a slight bug in your ConnectedPolyGroup.Init() method. I've moved ++m_GroupCount to below ProcessConnectedPolys() or your groupIDs are set too high in that method. Now it appears to be working as expected.

    Bool    done =                FALSE;  
  for(LONG polyNdx = 0L; polyNdx != m_numPolys; ++polyNdx)  
  {  
      if (m_pDstPolyProcessed[polyNdx])    continue;  
  
      // set group index/ID  
      m_pGroupIDs[polyNdx] =                m_GroupCount;  
      // mark this one off...  
      m_pDstPolyProcessed[polyNdx] =        1;  
      ++m_numMappedPolys;  
  
      // set all neighbors to same group index/ID  
      done =                                this->ProcessConnectedPolys();  
      // bump group index/ID for next group  
// THIS HAS BEEN MOVED TO BELOW ProcessConnectedPolys()!  
      ++m_GroupCount;  
      if (done)                            break;  
  }

Helper

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On 03/08/2012 at 10:03, xxxxxxxx wrote:

Hmm... I don't see any difference in what you posted and the latest posted code above (?). Maybe I found/fixed the post after you had already grabbed the code? Or am I missing something?

Helper

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On 03/08/2012 at 10:11, xxxxxxxx wrote:

Hehe...... Must have grabbed an earlier version of the code. Good that you found it too!

Helper

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On 03/08/2012 at 10:22, xxxxxxxx wrote:

I thought that might be the case :). I don't recall what other changes I made (and whether or not any changes were bug-fixes), so you might want to compare the rest of that to what you're using as well.

Helper

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On 03/08/2012 at 10:33, xxxxxxxx wrote:

Just for completeness, here is the latest in-use code...

  
class ConnectedPolyGroup  
{  
private:  
  Bool        m_bInit;  
  LONG        m_numVerts;  
  LONG        m_numPolys;  
  LONG        m_numMappedPolys;  
  LONG        m_GroupCount;  
  CPolygon    *m_pDstPolys;  
  UCHAR        *m_pDstPolyProcessed;  
  UCHAR        *m_pNeighborsAdded;  
  LONG        *m_pGroupIDs;  
  Neighbor    m_dstNbr;  
  
  Bool ProccessConnectedPolys(void);  
public:  
  void FreeData(void);  
  BaseSelect *SelectGroup(LONG GroupID);  
  LONG NumPolys(void)                        { return m_numPolys; }  
  LONG NumConnectedGroups(void)            { return m_GroupCount; }  
  LONG GroupID(LONG polyNdx)                { if(!m_bInit || polyNdx >= m_numPolys) return NOTOK;    return  m_pGroupIDs[polyNdx]; }  
  Bool Init(PolygonObject *pPolyObj);  
  
  ConnectedPolyGroup(void);  
  ~ConnectedPolyGroup(void);  
};  
  
ConnectedPolyGroup::ConnectedPolyGroup(void)  
{  
  m_bInit = false;  
  m_GroupCount = 0;  
  m_pDstPolyProcessed = NULL;  
  m_pNeighborsAdded = NULL;  
  m_pGroupIDs = NULL;  
}  
  
ConnectedPolyGroup::~ConnectedPolyGroup(void)  
{  
  this->FreeData();  
}  
  
void ConnectedPolyGroup::FreeData(void)  
{  
  bDelete(m_pDstPolyProcessed);  
  bDelete(m_pNeighborsAdded);  
  bDelete(m_pGroupIDs);  
  m_numMappedPolys = 0;  
  m_GroupCount = 0;  
  m_numVerts = 0;  
  m_numPolys = 0;  
  m_bInit = false;  
}  
  
// generate a BaseSelect based on connected GroupID - caller owns returned BaseSelect pointer  
BaseSelect *ConnectedPolyGroup::SelectGroup(LONG GroupID)  
{  
  if(!m_bInit || GroupID >= m_GroupCount)    return NULL;  
  
  BaseSelect *pSel = BaseSelect::Alloc();  
  if( !pSel )                                return NULL;  
  pSel->DeselectAll();    // <-- shouldn't actually be needed  
  
  LONG polyNdx;  
  for(polyNdx=0; polyNdx<m_numPolys; polyNdx++)  
  {  
      if( m_pGroupIDs[polyNdx] == GroupID )  
          pSel->Select(polyNdx);  
  }  
  return pSel;  
}  
  
Bool ConnectedPolyGroup::Init(PolygonObject *pPolyObj)  
{  
  this->FreeData();  
  
  m_numVerts = pPolyObj->GetPointCount();  
  m_numPolys = pPolyObj->GetPolygonCount();  
  m_pDstPolys = pPolyObj->GetPolygonW();  
  
  // track which polys have been processed.  
  m_pDstPolyProcessed = bNew UCHAR[m_numPolys];  
  if( !m_pDstPolyProcessed )        return false;  
  
  // track which polys have had their neighbors added.  
  m_pNeighborsAdded = bNew UCHAR[m_numPolys];  
  if( !m_pNeighborsAdded )        return false;  
  
  // track which 'connected group' each poly belongs to  
  m_pGroupIDs = bNew LONG[m_numPolys];  
  if( !m_pGroupIDs )                return false;  
  
  // initialize Neighbor class  
  if( !m_dstNbr.Init(m_numVerts, m_pDstPolys, m_numPolys, NULL) )    return false;  
  
  ClearMem(m_pDstPolyProcessed, m_numPolys * sizeof(UCHAR), 0);  
  ClearMem(m_pNeighborsAdded, m_numPolys * sizeof(UCHAR), 0);  
  ClearMem(m_pGroupIDs, m_numPolys * sizeof(LONG), 0);  
  
  LONG polyNdx;  
  Bool done = false;  
  for(polyNdx=0; polyNdx<m_numPolys; polyNdx++)  
  {  
      if( m_pDstPolyProcessed[polyNdx] )    continue;  
  
      m_pGroupIDs[polyNdx] = m_GroupCount;                        // set group index/ID  
      m_pDstPolyProcessed[polyNdx] = 1;                            // mark this one off...  
      m_numMappedPolys++;  
  
      done = this->ProccessConnectedPolys();                        // set all neighbors to same group index/ID  
  
      m_GroupCount++;                                                // bump group index/ID for next group  
      if( done )    break;  
  }  
  
  // done with these...  
  bDelete(m_pDstPolyProcessed);  
  bDelete(m_pNeighborsAdded);  
  m_bInit = true;  
  return true;  
}  
  
Bool ConnectedPolyGroup::ProccessConnectedPolys(void)  
{  
  Bool morePolys = true;  
  while( morePolys )  
  {  
      morePolys = false;  
      LONG polyNdx;  
      for(polyNdx=0; polyNdx<m_numPolys; polyNdx++)  
      {  
          if( !m_pDstPolyProcessed[polyNdx] )    continue;    // only adding/processing neighbors of previously matched/valid polys  
          if( m_pNeighborsAdded[polyNdx] )    continue;    // don't add/process neighbors if already added  
  
//            CPolygon *pDstPoly = &m_pDstPolys[polyNdx];  
          PolyInfo *pDstPolyInfo = m_dstNbr.GetPolyInfo(polyNdx);  
          LONG side;  
          for(side=0; side<4; side++)  
          {  
                  LONG dstNbrNdx = pDstPolyInfo->face[side];  
              if( dstNbrNdx == NOTOK )                continue;    // skip any sides that don't exist  
              if( m_pDstPolyProcessed[dstNbrNdx] )    continue;    // only adding neighbors not already added  
  
              m_pGroupIDs[dstNbrNdx] = m_GroupCount;        // all connected polys get the same index/ID  
              m_pDstPolyProcessed[dstNbrNdx] = 1;            // mark this one off...  
              m_numMappedPolys++;  
              morePolys = true;                            // since we added / processed another poly, make sure we loop again to get _it's_ neighbors  
          }  
          m_pNeighborsAdded[polyNdx] = 1;                    // we've processed this polys neighbors  
  
          if( m_numMappedPolys == m_numPolys )  
          {  
              morePolys = false;  
              break;    // return true?  
          }  
      }  
  }  
  if( m_numMappedPolys == m_numPolys )  
      return true;  
  return false;  
}

...I _think_ the only difference in that and what's posted above is that I go ahead and free a couple (no-longer-needed) arrays inside Init() instead of waiting for the Destructor.

As an aside, based on some later use of this base code (in this thread), I think that I determined that I didn't really need the m_pNeighborsAdded array/checking/tracking at all.

Helper

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On 04/08/2012 at 07:55, xxxxxxxx wrote:

Will compare code and update as needed. Thanks!